When it comes to operatic world premieres, experience suggests it's wise to keep your expectations low and your artistic tolerance high. Opera has evolved into a complex art form combining many virtuoso elements that must weave together with style and excellence for success of the whole.

The world premiere of Mark Adamo's "The Gospel of Mary Magdalene," at San Francisco's War Memorial Opera House last week, sadly stumbled and lost its way. However, the vocal, choral and orchestral performances along with production design and staging made a favorable impression overall. Admirable vocal contributions by the chorus (prepared by Ian Robertson) and some fine solo work by the principals strengthened the dramatic impact of the opera.

In her San Francisco Opera debut, mezzo-soprano Sasha Cooke turned in a magnificent Magdalene, as visually gorgeous as she was vocally splendid, transcending Adamo's clunky libretto with her charismatic portrayal. Baritone Nathan Gunn gave a solid account as Yeshua (Jesus), though at times was overpowered by the orchestra, which weakened his authority in the role. Soprano Maria Kanyova as Miriam (the mother of Yeshua) tended toward ear-bothering shrillness. Tenor William Burden sang a powerful portrayal of the misogynistic Peter, the apostle.

It is the job of art to stretch us and open us to new possibilities, expand perceptions and bring fresh vision to old ideas. Fundamental to this process is the willingness of organizations like the San Francisco Opera, and its general director David Gockley, to commission and support new creations; also for artists themselves to commit their best to these original works. This risk-taking for art is a significant and praiseworthy part of the Magdalene effort.

Adamo, who takes his place among the top opera composers of the day, alongside John Adams and Philip Glass, chooses themes about strong women and writes his own librettos. His first major opera, "Little Women," based on Louisa May Alcott's novel, opened in Houston to critical acclaim and has been produced more than 30 times since then. Less successful was his 2006 adaptation of the ancient Greek classic "Lysistrata" by Aristophanes, a comedy in which the women of Sparta and Athens go on a "sex-strike" to end the war-making of their husbands.

Placing the compelling and controversial Mary Magdalene at the center of his latest opus is a bold undertaking for the composer. A worthy figure for a culture actively evolving the role and voice of women, the paradoxical Magdalene makes an ideal heroine for challenging old paradigms.

Through her one can explore female spiritual power and passion, the Western esoteric mysteries of the divine feminine and Magdalene's role as Jesus' most respected disciple. You can consider the far-reaching implications of Jesus as a married man, rethink gender biases in the Bible and much more.

But this opera faltered at its core — Adamo's music, but especially his leaden storytelling. Though Adamo spent six years researching the Gnostic gospels and related materials, unhappily he delivered a soul-less and fragmented opera without a persuasive dramatic arc, leaving heads shaking at the missed opportunity.

Here's how he plays it out: The opera opens in an archeological dig in the Holy Land with choristers in modern dress grumbling about "poisonous" passages in the Bible denigrating women and the procreative act. They ask for a wholesome change in the story and, presto, Mary Magdalene materializes.

We find her pursuing mystical union with the divine through an erotic encounter with a man, and she sings an ecstatic aria to that effect. A genuine attention grabber, this scene promises a breakthrough message about sex and transcendence when she and Jesus finally get together.

Not so fast. Adamo wants to show the human side of these individuals freed from the pesky chains of the mysticism and "magic" of the traditional version. Yeshua saves her from stoning. They fall in love. He calls her Wisdom. She dubs him Nazarene. The jealous disciples complain vehemently about her power over him and his teaching, especially Peter. Many tussles ensue. Many themes and ideas scramble for attention. None succeed.

Yeshua's mother Miriam warns Magdalene that her troublesome son will ruin her if they marry. She implies that Yeshua is the illegitimate offspring of an illicit affair with a man whom she refuses to name. No virgin she. The first half finally culminates in the surprisingly tepid wedding night of the couple.

After two acts in three long hours, no resurrection takes place. Magdalene instead weeps in the tomb over Yeshua's inert body. His "ghost" appears behind her, rather like a thought bubble (she never looks at him), and asks her to tell their story wherever she wanders.

Alas, this alternate story, shorn of its charismatic, sacred and numinous elements, tumbles into the sphere of the ordinary. It's just a long and dreary tale about the self-directed and intelligent wife of a teaching rabbi with huge problems who is killed unjustly in the prime of his life. Not a saga for the ages.

Adamo's score is more appealing than his meandering, non-lyrical libretto. While it benefitted from expert execution by the orchestra, led by Michael Christie, its numerous flavorless passages accentuated the troubles with the tedious text.

Occasional vibrant bursts of brass and percussion, a few captivating arias along with flashes of choral and orchestral beauty, sparked a yearning for a whole operatic immersion in such an ecstatic soundscape. But it didn't happen. We were set adrift in a Nag Hammadi gnostic muddle.

"The Gospel of Mary Magdalene" plays through July 7 at San Francisco's War Memorial Opera House. For tickets and information call 415-864-3330 or see www.sfopera.com.